Metro area air quality · 2025

Mount Vernon, OH

Median AQI 40 (Good). 84.1% of monitored days rated Good across this metro's EPA monitoring network.

40
Median AQI
84.1%
Good-air days
1
Unhealthy days
74%
Cleaner than US metros

Aggregated from EPA Air Quality System (2025), 214 monitored days. EPA AQS →

The verdict

The Mount Vernon, OH metro runs good on the EPA scale, cleaner than the median US metro, a median AQI of 40 with 84.1% of 214 monitored days in the Good band.

40
median AQI · Good
84.1%
days rated Good
74%
cleaner than US metros
159
worst single reading

1 day reached Unhealthy or worse across the metro's monitors in 2025.

Insights: Mount Vernon, OH metro. Aggregated EPA AQS monitors across this Core-Based Statistical Area logged a median Air Quality Index of 40 over 214 measured days in 2025, which corresponds to a Good band and a Good metro-wide health grade. The monitored-day split lands at 180 Good days (84%), 32 Moderate (15%), and 1 Unhealthy-for-Sensitive-Groups (0%). The 90th-percentile AQI finished at 54 while the highest single-day reading hit 159 (Unhealthy). Metro residents averaged roughly 25.2 clean-air days per 30-day window across the reporting year.

Across the 2020–2025 trend window, good days shifted by -46 and the median AQI moved +2 points, which classifies the multi-year trajectory as worsening. The metro recorded 1 unhealthy-or-worse days combined, on those days the EPA recommends that sensitive groups limit prolonged outdoor exertion, and many schools and athletic programs adjust outdoor activity accordingly. Metros with comparable AQI profiles include Berlin, NH-VT (85.4% good, AQI 40); Burlington-South Burlington, VT (91.2% good, AQI 40); Cambridge, MD (84.4% good, AQI 40).

Air Quality Summary

Median AQI

40

Good

Good Days

84.1%

180 of 214 days

Max AQI

159

Unhealthy

Health Grade

Good

90th pct: 54

AQI Day Breakdown (2025)

Distribution of 214 monitored days across EPA AQI categories.

Good

180

84%

Moderate

32

15%

USG

1

0%

Unhealthy

1

0%

Very Unhealthy

0

0%

Hazardous

0

0%

Health Impact Assessment

Good

The Mount Vernon, OH metro area's air quality is rated Good based on 84.1% good air days. There were 1 unhealthy days in 2025 when outdoor activity should be limited.

Air quality is acceptable most days, but 1 days reached "Unhealthy for Sensitive Groups" and peak AQI reached 159. Sensitive groups should monitor real-time conditions at AirNow.gov.

How does the Mount Vernon, OH metro compare?

How Mount Vernon, OH compares

Good-day share better than US avg
Mount Vernon, OH 84.1%
Berlin, NH-VT 85.4%
US average 71.3%
Median AQI better than US avg
Mount Vernon, OH 40
Berlin, NH-VT 40
US average 41
Unhealthy days / yr about average
Mount Vernon, OH 1
Berlin, NH-VT 0
US average 1

5-Year Air Quality Trend

Air quality is worsening in the Mount Vernon, OH metro. Best year: 2020 (226 good days).

Year Good Moderate Unhealthy Median AQI
2020 226 19 0 38
2021 225 20 0 38
2022 225 19 0 39
2023 200 44 0 42
2024 208 36 0 41
2025 180 32 1 40

Metros with Similar Air Quality

Metro areas across the US with a similar median AQI to Mount Vernon, OH.

Berlin, NH-VT

AQI 40 · 85.4% good

40

Burlington-South Burlington, VT

AQI 40 · 91.2% good

40

Cambridge, MD

AQI 40 · 84.4% good

40

Charleston, WV

AQI 40 · 79.6% good

40

Corning, NY

AQI 40 · 80.2% good

40

Dickinson, ND

AQI 40 · 80.3% good

40

More Air Quality Data

Explore EPA air quality rankings and guides across U.S. metros and counties.

Cleanest Metro Areas

U.S. metros ranked by their share of Good air-quality days.

Worst Air Quality

Counties and metros with the most unhealthy air days.

All Metro Areas

Annual AQI by CBSA for every monitored U.S. metro area.

Best and Worst City Air

What drives urban air quality and how metro areas compare.

Air Quality Guides

Frequently Asked Questions

What is the air quality in the Mount Vernon, OH metro area? ▼
The Mount Vernon, OH metro area has a median Air Quality Index (AQI) of 40, rated "Good." 84.1% of monitored days (180 out of 214) had good air quality in 2025.
How many unhealthy air days does Mount Vernon, OH have? ▼
In 2025, the Mount Vernon, OH metro area recorded 1 unhealthy air days (1 Unhealthy, 0 Very Unhealthy, 0 Hazardous). The maximum AQI reached 159.
Is air quality in Mount Vernon, OH getting better or worse? ▼
Air quality in the Mount Vernon, OH metro is worsening based on 5-year trends (2020-2025). Best year: 2020 with 226 good days. Worst year: 2025 with 180 good days.
What does AQI 40 mean for health? ▼
An AQI of 40 is "Good", air quality is satisfactory and poses little or no health risk. This is the best category on the EPA's AQI scale.
What is the 90th percentile AQI for Mount Vernon, OH? ▼
The 90th percentile AQI for the Mount Vernon, OH metro area is 54, meaning 90% of monitored days had an AQI at or below this level. The maximum AQI recorded was 159 (Unhealthy).
How does Mount Vernon, OH compare to other metro areas? ▼
The Mount Vernon, OH metro has 84.1% good air days. Similar metros: Berlin, NH-VT (85.4% good), Burlington-South Burlington, VT (91.2% good), Cambridge, MD (84.4% good).

Data Sources

Primary Source: U.S. Environmental Protection Agency (EPA), Air Quality System (AQS), Annual AQI by CBSA dataset, 2020–2025. See our methodology for how AQI, median, and coverage figures are computed.

Read our methodology , how this data is sourced, computed, and verified.

Source: U.S. EPA Air Quality System (AQS) Annual AQI by CBSA summary files (metro-level) · 2020–2025

Every figure on PlainAir is rendered directly from EPA AQS air-quality monitoring data, no number is typed in by an editor. This page draws directly on EPA AQS air-quality monitoring data, no figure is typed in by an editor. See our editorial standards & corrections policy, the methodology behind these numbers, or report a data error.